Systems and methods for micro impulse radar detection of physiological information

ABSTRACT

A micro impulse radar (MIR) system includes an MIR transceiver circuit configured to transmit, towards a subject, at least one transmitted radar signal, and receive at least one radar return signal. The system includes a control circuit configured to generate a control signal defining a radar signal parameter of the at least one transmitted radar signal, provide the control signal to the MIR transceiver circuit to cause the MIR transceiver circuit to transmit the at least one transmitted signal based on the radar signal parameter, and determine, based on the at least one radar return signal, a physiological parameter of the subject.

CROSS-REFERENCE TO RELATED APPLICATIONS

The present disclosure claims the benefit of and priority to U.S.Provisional Application No. 62/747,614, titled “SYSTEMS AND METHODS FORMICRO IMPULSE RADAR DETECTION OF PHYSIOLOGICAL INFORMATION,” filed Oct.18, 2018, and U.S. Provisional Application No. 62/813,620, titled“SYSTEMS AND METHODS OF RADAR DETECTION OF PHYSIOLOGICAL INFORMATION,”filed Mar. 4, 2019, the disclosures of which are incorporated herein byreference in their entireties.

BACKGROUND

The present disclosure relates generally to the field of radar. Moreparticularly, the present disclosure relates to systems and methods forradar detection of physiological information.

Radar systems can output signals that can be used to detect informationregarding various subjects, including human subjects. Micro impulseradar (MIR) systems can output wideband signals that have relatively lowpower requirements. MIR systems can be relatively inexpensive tomanufacture, as compared to existing radar systems.

SUMMARY

At least one embodiment relates to micro impulse radar (MIR) system. Thesystem includes an MIR transceiver circuit configured to transmit,towards a subject, at least one transmitted radar signal; and receive atleast one radar return signal. The system includes a control circuitconfigured to generate a control signal defining a radar signalparameter of the at least one transmitted radar signal; provide thecontrol signal to the MIR transceiver circuit to cause the MIRtransceiver circuit to transmit the at least one transmitted signalbased on the radar signal parameter; and determine, based on the atleast one radar return signal, a physiological parameter of the subject.

Another embodiment relates to a method. The method includes generating,by a control circuit, a control signal defining a radar signal parameterof a transmitted radar signal; providing, by the control circuit, thecontrol signal to an MIR transceiver circuit; transmitting, by the MIRtransceiver circuit, the transmitted radar signal based on the radarsignal parameter; receiving, by the MIR transceiver circuit, a radarreturn signal; and determining, by the control circuit based on theradar return signal, a physiological parameter of a subject.

Another embodiment relates to a system. The system includes a microimpulse radar (MIR) sensor configured to receive a plurality of radarreturns corresponding to an MIR radar signal transmitted towards asubject; and a control circuit configured to calculate a physiologicalparameter of the subject based on the plurality of radar returns.

Another embodiment relates to a method. The method includes receiving,by a micro impulse radar (MIR) sensor, a plurality of radar returnscorresponding to an MIR radar signal transmitted towards a subject; andcalculating, by a control circuit, a physiological parameter of thesubject based on the plurality of radar returns.

Another embodiment relates to a system. The system includes a housingconfigured to be coupled to a subject; a sensor mounted in the housing,the sensor configured to detect information regarding the subject; and acontrol circuit coupled to the sensor, the control circuit configured tocalculate a physiological parameter regarding the subject based on theinformation detected by the sensor.

Another embodiment relates to a method. The method includes detecting,by a sensor mounted in a housing coupled to a subject, informationregarding the subject; and calculating, by a control circuit coupled tothe sensor, a physiological parameter regarding the subject based on theinformation detected by the sensor.

This summary is illustrative only and is not intended to be in any waylimiting.

BRIEF DESCRIPTION OF THE DRAWINGS

The disclosure will become more fully understood from the followingdetailed description, taken in conjunction with the accompanyingfigures, wherein like reference numerals refer to like elements, inwhich:

FIG. 1 is a schematic diagram of an MIR system in accordance with anembodiment of the present disclosure.

FIG. 2 is a schematic diagram of a transceiver of the MIR system of FIG.1.

FIG. 3 is a block diagram of an MIR system in accordance with anembodiment of the present disclosure.

FIG. 4 is a block diagram of processing modules of the MIR system ofFIG. 3.

FIG. 5 is a schematic diagram of a portable MIR system in accordancewith an embodiment of the present disclosure.

FIG. 6 is a flow diagram of a method of operating an MIR system inaccordance with an embodiment of the present disclosure.

DETAILED DESCRIPTION

Before turning to the figures, which illustrate certain exemplaryembodiments in detail, it should be understood that the presentdisclosure is not limited to the details or methodology set forth in thedescription or illustrated in the figures. It should also be understoodthat the terminology used herein is for the purpose of description onlyand should not be regarded as limiting.

Systems and Methods of Radar Detection of Physiological Information

Referring now to FIGS. 1-2, a radar system 110 is shown according to anembodiment of the present disclosure. The radar system 110 is used todetect physiological information regarding a subject 100. The subject100 may be a living subject, such as a mammalian (e.g., human) subject.

The radar system 110 includes a transmitter circuit 112 and a receivercircuit 114. The transmitter circuit 112 can transmit a first radarsignal 116, such as in a direction towards the subject 100. For example,the transmitter circuit 112 can include a pulse generator 208 thatapplies a voltage to a transmit antenna 204 to cause the transmitantenna 204 to output the first radar signal 116. The transmittercircuit 112 can generate the first radar signal 116 to be an MIR signal.Various functions and systems described herein may be implemented usingMIR signals as well as radar signals of other modalities andfrequencies. The pulse generator 208 can apply the voltage in shortpulses to generate MIR signals. For example, the pulses may have risetimes on the order of picoseconds, and the pulse generator can generatethe pulses on the order of millions of pulses per second. In someembodiments, a pulse width of the pulse outputted by the pulse generatoris between approximately two hundred picoseconds and five nanoseconds.The pulse can be a relatively wideband pulse in terms of frequency, ascompared to typical radar systems.

The receiver circuit 114 can include a receive antenna 212 (which may beco-located with/the same as the transmit antenna 204 of the transmittercircuit 112, or may be separate from the transmit antenna 204) and apulse receiver 216. The receiver circuit 114 can receive a second radarsignal 118 at the receive antenna 212, which can correspond to the firstradar signal 116. For example, the second radar signal 118 can be aradar return signal corresponding to the first radar signal 116. Thesecond radar signal 118 can result from interaction of the first radarsignal 116 and the subject 100. For example, the second radar signal 118(e.g., return signal) can result from transmission, reflection,refraction, absorption (and later emission), shadowing, or otherwisescattering of the first radar signal 116 by the subject 100, or variouscombinations, such as multi-path combinations, thereof. Various signalsmay be described herein as first, second, third, or further numberedsignals, which may refer to aspects of one or more signals at variouspoints in space, time, output, or reception. In some embodiments, thereceiver circuit 114 controls timing of reception of the second radarsignal 118 so that a detection range of the receiver circuit 114 isrelatively small. For example, the receiver circuit 114 can use anexpected round-trip time of flight of the first radar signal 116 and thesecond radar signal 118 to maintain the detection range below athreshold detection range. In some embodiments, the threshold detectionrange is on the order of feet. In some embodiments, the thresholddetection range is on the order of inches or less (e.g., for portableradar system 120). As such, the radar system 110 can maintain arelatively high signal to noise ratio by focusing on second radarsignals 118 for which the radar system 110 can have a high confidence ofcorresponding to interaction of the first radar signals 116 with thesubject 100. The pulse receiver 216 can receive the second radar signal118 via the receive antenna 212 and generate an electronic signal (e.g.,analog signal, radio frequency signal) corresponding to the second radarsignal 118 for further analysis. The radar system 110 can receive andtransmit the signals 116, 118 to detect a physiological parameterregarding the subject 100.

As shown in FIG. 1, a portable radar system 120 may be provided. Theportable radar system 120 may be similar to the radar system 110, suchas to output radar signals and receive return radar signalscorresponding to the outputted radar signals. The portable radar system120 may include straps, adhesives, or other attachment members to enablethe portable radar system 120 to be worn by the subject 100.

Referring now to FIGS. 3-4, a radar system 300 is shown according to anembodiment of the present disclosure. The radar system 300 canincorporate features of the radar system 110, 120 described withreference to FIGS. 1-2.

The radar system 300 includes an MIR transceiver circuit 302 includingan MIR transmitter 306 and an MIR receiver 304, and a processing circuit312. The MIR transmitter 306 can incorporate features of the transmittercircuit 112 described with reference to FIGS. 1-2, and the MIR receiver304 can incorporate features of the receiver circuit 114 described withreference to FIGS. 1-2. For example, the MIR transmitter 306 cantransmit a first radar signal towards a subject, and the MIR receiver304 can receive a second radar signal corresponding to the first radarsignal.

The processing circuit 312 includes a processor 314 and memory 316. Theprocessor 314 may be implemented as a specific purpose processor, anapplication specific integrated circuit (ASIC), one or more fieldprogrammable gate arrays (FPGAs), a system on a chip (SoC), a group ofprocessing components (e.g., multicore processor), or other suitableelectronic processing components. The memory 316 is one or more devices(e.g., RAM, ROM, flash memory, hard disk storage) for storing data andcomputer code for completing and facilitating the various user or clientprocesses, layers, and modules described in the present disclosure. Thememory 316 may be or include volatile memory or non-volatile memory andmay include database components, object code components, scriptcomponents, or any other type of information structure for supportingthe various activities and information structures of the inventiveconcepts disclosed herein. The memory 316 is communicably connected tothe processor 314 and includes computer code or instruction modules forexecuting one or more processes described herein. The memory 316includes various circuits, software engines, and/or modules that causethe processor 314 to execute the systems and methods described herein.

As shown in FIG. 4, the memory 316 can include a control signalgenerator 404, a historical database 412, a parameter calculator 408,each of which the processor 314 can execute to perform the systems andmethods described herein. The processing circuit 312 may be distributedacross multiple devices. For example, a first portion of the processingcircuit 312 that includes and executes the control signal generator 404may be mechanically coupled to the transceiver circuit 302, while asecond portion of the processing circuit 312 that includes an executesthe parameter calculator 408, historical database 412, health conditioncalculator 416, and/or analytics engine 420 may be remote from the firstportion and communicably coupled to the first portion (e.g., usingcommunications circuit 318).

The radar system 300 can include an image capture device 308. The imagecapture device 308 can capture images regarding the subject 100, andprovide the images to the processing circuit 312 (e.g., to historicaldatabase 412).

The processing circuit 312 can execute object recognition and/orlocation estimation using the images captured by the image capturedevice 308. For example, the processing circuit 312 can extract, from areceived image, features such as shapes, colors, edges, and/or spatialrelationships between pixels of the received images. The processingcircuit 312 can compare the extracted features to template features(e.g., a template of a human subject), and recognize objects of theimages based on the comparison, such as by determining a result of thecomparison to satisfy a match condition. The template can include anexpected shape of the subject 100. In some embodiments, the processingcircuit 312 can estimate the location of anatomical features of thesubject 100 based on the receive image, such as by estimating a locationof a heart, lungs, or womb of the subject 100 based on having detectedthe subject 100.

The radar system 300 can include a position sensor 310. The positionsensor 310 can detect a pose (e.g., at least one of a position or anorientation) of one or more components of the radar system 300. Forexample, the position sensor 310 can detect a pose of the MIR receiver304 and detect a pose of the MIR transmitter 306. The position sensor310 can include various sensors, such as accelerometers,

The radar system 300 can include a communications circuit 318. Thecommunications circuit 318 can include wired or wireless interfaces(e.g., jacks, antennas, transmitters, receivers, transceivers, wireterminals, etc.) for conducting data communications with varioussystems, devices, or networks. For example, the communications circuit318 can include an Ethernet card and port for sending and receiving datavia an Ethernet-based communications network. The communications circuit318 can include a WiFi transceiver for communicating via a wirelesscommunications network. The communications circuit 318 can communicatevia local area networks (e.g., a building LAN), wide area networks(e.g., the Internet, a cellular network), and/or conduct directcommunications (e.g., NFC, Bluetooth). In some embodiments, thecommunications circuit 318 can conduct wired and/or wirelesscommunications. For example, the communications circuit 318 can includeone or more wireless transceivers (e.g., a Wi-Fi transceiver, aBluetooth transceiver, a NFC transceiver, a cellular transceiver).

In some embodiments, the radar system 300 includes a user interface 320.The user interface 320 can receive user input and present informationregarding operation of the radar system 300. The user interface 320 mayinclude one or more user input devices, such as buttons, dials, sliders,or keys, to receive input from a user. The user interface 320 mayinclude one or more display devices (e.g., OLED, LED, LCD, CRTdisplays), speakers, tactile feedback devices, or other output devicesto provide information to a user.

Control Signal Generator

The control signal generator 404 controls operation of the MIRtransceiver circuit 302. The control signal generator 404 can generate acontrol signal defining a radar signal parameter of the first radarsignal to be transmitted by the MIR transmitter 306. The control signalgenerator 404 can define the radar signal parameter to include at leastone of a frequency, an amplitude, a pulse width, or a pulse repetitionfrequency of the first radar signal.

In some embodiments, the control signal generator 404 defines the radarsignal parameter based on an expected response of the subject to thefirst radar signal and/or an expected response of the first radar signalto the subject. For example, the control signal generator 404 can definethe radar signal parameter based on an expected physical response thatcauses the second radar signal to have an expected signal to have anexpected signal to noise ratio for a physiological parameter that thecontrol signal generator 404 determines based on the second radarsignal. The expected responses can correspond to factors such as whetherthe first radar signal will be reflected by an outer surface of thesubject 100 (e.g., including clothing worn by the subject), willpenetrate the subject 100 before being absorbed or reflected, or adistance the first radar signal is expected to penetrate the subject100. In some embodiments, the control signal generator 404 estimates theexpected physical response based on biological and/or anatomicalfeatures of the subject 100, such as regions that the MIR transceivercircuit 302 targets that may be primarily composed of water molecules ascompared to bone structures. For example, the control signal generator404 can define the radar signal parameter so that the outputted firstradar signals have a particular frequency, amplitude, pulse width,and/or pulse repetition frequency.

The control signal generator 404 can define the radar signal parameterby determining the expected response based on an actual signal to noiseratio of a prior received radar signal. For example, the control signalgenerator 404 can retrieve from the historical database 412 the actualsignal to noise ratio of the prior received radar signal, a historicalradar signal parameter corresponding to the prior received radar signal,and a parameter of the subject 100 corresponding to the prior receivedradar signal, and determine the expected response by comparing the dataretrieved from the historical database 412 to corresponding dataregarding operation of the radar system 300 to probe the subject 100.The parameter of the subject 100 may include a distance from the radarsystem 300 to the subject 100, or a location of a particular anatomicalfeature of the subject 100.

The control signal generator 404 can apply noise to the control signal,such as to randomize a pulse rate of the control signal. By applyingnoise to the control signal, the control signal generator 404 canuniquely encode the control signal, and thus the transmitted radarsignal transmitted by the MIR transceiver circuit 302. In addition,applying noise can reduce the effect of interference from otherelectromagnetic radiation sources.

In some embodiments, the control signal generator 404 controls operationof the MIR receiver 304. For example, the control signal generator 404can control a range gate of the MIR receiver 304. The range gate cancorrespond to an expected round trip time of the transmitted radarsignal transmitted by the MIR transmitter 306 and the correspondingradar return signal received by the MIR receiver 304 based oninteraction with the subject 100. For example, the control signalgenerator 404 can use a distance to the subject 100 to control the rangegate. In some embodiments, the control signal generator 404 uses alocation of a particular anatomical feature of the subject 100, such asthe heart or lungs, to control the range gate.

Parameter Calculator

The parameter calculator 408 can determine, based on the second radarsignal, a physiological parameter of the subject. For example, theparameter calculator 408 can calculate, based on the second radarsignal, parameters such as locations of anatomical features, sizes ofanatomical features, movement of anatomical features, movement of fluids(e.g., blood flow), or velocity data. The parameter calculator 408 canexecute a Doppler algorithm to calculate velocity data. The parametercalculator 408 can calculate information such as an amplitude or powerof the radar return signals at various frequencies, such as to generatea spectral analysis of the radar return signal. The parameter calculator408 can calculate the physiological parameter to include at least one ofa cardiac parameter, a pulmonary parameter, a blood flow parameter, or afetal parameter based on the radar return signals. The parametercalculator 408 can calculate multiple parameters based on the radarreturn signal, such as by deconvolving the radar return signal. Theradar return signal can include any of a variety of return signalsincluding reflected, absorbed, refracted, or scattered signals, orcombinations thereof, including multi-path signals.

In some embodiments, the parameter calculator 408 calculates thephysiological parameter using at least one of a predetermined templateor a parameter function. The predetermined template may include featuressuch as expected signal amplitudes at certain frequencies, or pulseshapes of the radar return signal. The predetermined template mayinclude anatomical features, such as shapes of vessel walls or cavitywalls, such that the parameter calculator 408 can identify the movementof anatomical features (as well as blood flow and other fluid flow). Theparameter function may be configured to convert data of the radar returnsignal (e.g., amplitude as a function of time at various frequencies)into various other variables, such as velocity or periodicity.

In some embodiments, the parameter calculator 408 calculates thephysiological parameter based on an indication of a type of thephysiological parameter. For example, the parameter calculator 408 canreceive the indication based on user input. The parameter calculator 408can determine the indication, such as by determining an expectedanatomical feature of the subject 100 that the radar system 300 isprobing using the transmitted radar signal. For example, the parametercalculator 408 can use image data from image capture device 308 todetermine that the radar system 300 is probing a heart of the subject100, and determine the type of the physiological parameter to be acardiac parameter. The parameter calculator 408 can use the image dataand the radar return signal to determine the type of the physiologicalparameter (e.g., to generate a candidate match between the radar returnsignal and the type of the physiological parameter and use the candidatematch to adjust matching between the image data and template featuresrepresentative of the expected anatomical feature). The parametercalculator 408 may use the determined type of the physiologicalparameter to select a particular predetermined template or parameterfunction to execute, or to increase a confidence that the radar returnsignal represents the type of physiological parameter (which may beuseful for calculating the physiological parameter based on comparingthe radar return signal to predetermined template(s) and searching for amatch accordingly).

In some embodiments, the parameter calculator 408 calculates the cardiacparameter to include at least one of a heart volume, a heart rate, aheart stroke volume, a heart rate variation, a pulse shape, a heartpumping efficiency, or a cycle-to-cycle variation. For example, theparameter calculator 408 can extract a periodicity from the radar returnsignal to calculate the heart rate, and can monitor the periodicityacross various cycles to calculate the heart rate variation. Theparameter calculator 408 can use one or more pulse shape templates tocalculate the pulse shape represented by the radar return signal. Theparameter calculator 408 can monitor for changes in amplitude of theradar return signal at various frequencies to calculate thecycle-to-cycle variation. The cardiac parameter determined by theparameter calculator 408 can be used as a fingerprint (e.g., uniqueidentifier) regarding the subject 100, which can be maintained in adatabase of the system 300 or outputted to remote devices.

The parameter calculator 408 can calculate the pulmonary parameter toinclude at least one of a breathing rate, a breathing rate variation, avolume in a chest of the subject 100, a volume change in the chest ofthe subject, or an air exchange efficiency. The parameter calculator 408can determine the breathing rate based on a periodicity extracted fromthe radar return signal, including a periodic movement of walls of thelungs (e.g., determined using a shape template corresponding to thewalls of the lungs). The parameter calculator 408 can determine thebreathing rate variation by monitoring the breathing rate over severalcycles. The parameter calculator 408 can determine the volume in thechest by determining the locations and/or shapes of walls of the lungs,and the volume change in the chest based on the volume and the periodicmovement of the walls of the lungs. The parameter calculator 408 cancalculate the air exchange efficiency (e.g., gas exchange efficiency) bymonitoring parameters that may be associated with gas exchange, such asventilation and/or perfusion parameters.

In some embodiments, the parameter calculator 408 calculates the fetalparameter to include similar parameters as the cardiac and/or pulmonaryparameters. The parameter calculator 408 can use predetermined templatesand/or parameter functions that have different characteristics specificto the fetal parameters (e.g., based on an expectation that a fetalheart rate is faster than an adult heart rate). The parameter calculator408 can calculate the fetal parameter to include similar parameters asused for fetal ultrasound, such as a volume of amniotic fluid, fetalposition, gestational age, or birth defects.

Historical Database

The historical database 412 can maintain historical data regarding aplurality of subjects, radar signals received for each subject,physiological parameters calculated for each subject, and radar systemoperations—for example, radar signal parameters—corresponding to thephysiological parameters calculated for each subject. For example, thehistorical database 412 can assign, to each subject, a plurality of datastructures each including a radar signal parameter of a first radarsignal transmitted to probe the subject, a second radar signal receivedin return, and a physiological parameter calculated based on the secondradar signal. The historical database 412 can maintain indications ofintended physiological features to be probed using the radar signals(e.g., heart, lungs) and/or types of the calculated physiologicalparameters (e.g., cardiac, pulmonary). The historical database 412 canassign to each subject various demographic data (e.g., age, sex, height,weight).

The historical database 412 can maintain various parameters calculatedbased on radar return signals. For example, the historical database 412can maintain physiological parameters, signal to noise ratios, healthconditions, and other parameters described herein that the processingcircuit 312 calculates using the radar return signals. The processingcircuit 312 can update the historical database 412 when additional radarreturn signals are received and analyzed. The historical database 412may include identifiers associated with one or more subjects andcorresponding known parameters regarding the one or more subjects, suchas physiological parameters (e.g., cardiac parameters, pulmonaryparameters, biometric parameters) or templates or reference pointscorresponding to the known parameters regarding the subjects. Theprocessing circuit 312 can use the parameter calculator 408 to generatea parameter of the subject 100, and compare the parameter of the subject100 to one or more known parameters maintained by the historicaldatabase 412 regarding the one or more subjects to identify the subject100 (e.g., compare the parameter determined by the parameter calculator408 to the known parameters to generate one or more match scores,evaluate the match score using a threshold, and determine a selectedknown parameter to match the parameter of the subject 100 responsive tothe match score satisfying the threshold). As such, the processingcircuit 312 can retrieve an identifier of the subject 100 based onmatching the parameter determined by the parameter calculator 408 to theknown parameters maintained in the historical database 412. Theprocessing circuit 312 can use the identifier for personalidentification of the subject 100 for various purposes, including butnot limited to retrieving thresholds for generating alerts specific tothe subject 100 or identifying the subject 100 for security or gateentry purposes.

Health Condition Calculator

In some embodiments, the radar system 300 includes the health conditioncalculator 416. The health condition calculator 416 can use thephysiological parameters calculated by the parameter calculator 408and/or the historical data maintained by the historical database 412 tocalculate a likelihood of the subject 100 having a particular healthcondition. The health condition calculator 416 can calculate likelihoodsassociated with medical conditions, emotion conditions, physiologicalconditions, or other health conditions.

In some embodiments, the health condition calculator 416 predicts alikelihood of the subject 100 having the health condition by comparingthe physiological parameter to at least one of (i) historical values ofthe physiological parameter associated with the subject (e.g., asmaintained in the historical database 412) or (ii) a predetermined valueof the physiological parameter associated with the medical condition(e.g., a predetermined value corresponding to a match condition asdescribed below). For example, the health condition calculator 416 cancalculate an average value over time of the physiological parameter todetermine a normal value or range of values for the subject 100, anddetermine the likelihood of the subject 100 having the medical conditionbased on a difference between the physiological parameter and theaverage value.

The health condition calculator 416 can maintain a match conditionassociated with each health condition. The match condition can includeone or more thresholds indicative of radar return data and/orphysiological parameters that match the health condition. As an example,the health condition calculator 416 can determine a likelihood of thesubject 100 having arrhythmia by comparing a heart rate of the subject100 to at least one of a minimum heart rate threshold (e.g., a thresholdbelow which the subject 100 is likely to have arrhythmia) or a maximumheart rate threshold (e.g., a threshold above which the subject 100 islikely to have arrhythmia), and output the likelihood of the subjecthaving arrhythmia based on the comparison. The health conditioncalculator 416 can store the outputted likelihoods in the historicaldatabase 412.

In some embodiments, the health condition calculator 416 updates thematch conditions based on external input. For example, the healthcondition calculator 416 can receive a user input indicating a healthcondition that the subject 100 has; the user input may also include anindication of a confidence level regarding the health condition. Thehealth condition calculator 416 can adjust the match condition, such asby adjusting the one or more thresholds of the match condition, so thatthe match condition more accurately represents the information of theexternal input. In some embodiments, the health condition calculator 416updates the match condition by providing the external input as trainingdata to the analytics engine 420.

The health condition calculator 416 can determine the likelihood of thesubject 100 having the medical condition based on data regarding aplurality of subjects. For example, the historical database 412 canmaintain radar return data, physiological parameter data, and medicalconditional data regarding a plurality of subjects (which the analyticsengine 420 can use to generate richer and more accurate parametermodels). The health condition calculator 416 can calculate a statisticalmeasure of a physiological parameter (e.g., average value, median value)for the plurality of subjects, and calculate an indication of thephysiological parameter of the subject 100 being abnormal and/orcalculate a likelihood of the subject 100 having the medical conditionbased on the statistical measure. In some embodiments, the healthcondition calculator 416 determines a likelihood that the subject 100has a condition, such as sepsis, using the cardiac parameter determinedby the parameter calculator 408. For example, the health conditioncalculator 416 can monitor at least one of the heart volume or thepumping efficiency determined by the parameter calculator 408, comparethe monitored parameter to a corresponding threshold (which may be apredetermined threshold or a threshold specific to the subject 100), andoutput a likelihood of the subject 100 having sepsis or anothercondition related to the cardiac parameter based on the comparison. Theradar system 300 can generate an alert regarding the conditionresponsive to the likelihood of the subject 100 having the condition,which may be able to be generated before other indicators are able todetect the condition (e.g., the condition, such as sepsis, may be ableto be detected before an EKG or other heart monitoring sensor outputsdata indicative of the condition due to changes in blood volume pumpedby the heart occurring before detectable changes in electrical activityof the heart).

Analytics Engine

In some embodiments, the radar system 300 includes an analytics engine420. The analytics engine 420 can be used to calculate variousparameters described herein, including where relatively large amounts ofdata may need to be analyzed to calculate parameters as well as thethresholds used to evaluate those parameters. For example, the parametercalculator 408 can execute the analytics engine 420 to determine thethresholds used to recognize physiological parameters. The healthcondition calculator 416 can execute the analytics engine 420 todetermine the thresholds used to determine whether physiologicalparameters indicate that the subject 100 has a particular medicalcondition. In some embodiments, the parameter calculator 408 can executethe analytics engine 420 to calculate a plurality of parameters based onthe second radar signal. For example, the analytics engine 420 cancalculate each of a cardiac parameter and a pulmonary parameter based onthe second radar signal. The analytics engine 420 can determine severalparameters by deconvolving the second radar signal, as the second radarsignal may represent a convolution of multiple parameters, such as heartrate, heart volume, heart contractions, and breathing rate. Theanalytics engine 420 may execute various algorithms to extract theplurality of parameters from the second radar signal, including machinelearning algorithms described herein that may provide models of theparameters to be extracted. The analytics engine 420 can operate variousmodels, engines, functions, filters, equations, algorithms, orcombinations thereof to generate information based on sensor dataacquired by the system 300.

In some embodiments, the analytics engine 420 includes a parametermodel. The analytics engine 420 can use training data including inputdata and corresponding output parameters to train the parameter model byproviding the input data as an input to the parameter model, causing theparameter model to calculate a model output based on the input data,comparing the model output to the output parameters of the trainingdata, and modifying the parameter model to reduce a difference betweenthe model output and the output parameters of the training data (e.g.,until the difference is less than a nominal threshold). For example, theanalytics engine 420 can execute an objective function (e.g., costfunction) based on the model output and the output parameters of thetraining data.

The parameter model can include various machine learning models that theanalytics engine 420 can train using training data and/or the historicaldatabase 412. The analytics engine 420 can execute supervised learningto train the parameter model. In some embodiments, the parameter modelincludes a classification model. In some embodiments, the parametermodel includes a regression model. In some embodiments, the parametermodel includes a support vector machine (SVM). In some embodiments, theparameter model includes a Markov decision process engine.

In some embodiments, the parameter model includes a neural network. Theneural network can include a plurality of layers each including one ormore nodes (e.g., neurons, perceptrons), such as a first layer (e.g., aninput layer), a second layer (e.g., an output layer), and one or morehidden layers. The neural network can include characteristics suchweights and biases associated with computations that can be performedbetween nodes of layers, which the analytics engine 420 can modify totrain the neural network. In some embodiments, the neural networkincludes a convolutional neural network (CNN). The analytics engine 420can provide the input from the training data and/or historical database412 in an image-based format (e.g., computed radar values mapped inspatial dimensions), which can improve performance of the CNN ascompared to existing systems, such as by reducing computationalrequirements for achieving desired accuracy in calculating healthconditions. The CNN can include one or more convolution layers, whichcan execute a convolution on values received from nodes of a precedinglayer, such as to locally filter the values received from the nodes ofthe preceding layer. The CNN can include one or more pooling layers,which can be used to reduce a spatial size of the values received fromthe nodes of the preceding layer, such as by implementing a max poolingfunction, an average pooling function, or other pooling functions. TheCNN can include one or more pooling layers between convolution layers.The CNN can include one or more fully connected layers, which may besimilar to layers of neural networks by connecting every node in fullyconnected layer to every node in the preceding layer (as compared tonodes of the convolution layer(s), which are connected to less than allof the nodes of the preceding layer).

The analytics engine 420 can train the parameter model by providinginput from the training data and/or historical database 412 as an inputto the parameter model, causing the parameter model to generate modeloutput using the input, modifying a characteristic of the parametermodel using an objective function (e.g., loss function), such as toreduce a difference between the model output and the and thecorresponding output of the training data. In some embodiments, theanalytics engine 420 executes an optimization algorithm that can modifycharacteristics of the parameter model, such as weights or biases of theparameter model, to reduce the difference. The analytics engine 420 canexecute the optimization algorithm until a convergence condition isachieved (e.g., a number of optimization iterations is completed; thedifference is reduced to be less than a threshold difference).

As described further below, the analytics engine 420 can train theparameter model using input from multiple sensor modalities. By usinginput from multiple sensor modalities, such as MIR andelectrocardiography to analyze cardiac parameters, the analytics engine420 can more accurately train the parameter model and improve operationof the radar system 300, as the input from multiple sensor modalitiesrepresents multiple, independent sets of correlated data. For example,both the MIR data and electrocardiography data can be independentlydetermined to represent cycle-to-cycle variation, increasing theaccuracy of the parameter model when these independent data sets arecorrelated in training the parameter model.

Pose Control

In some embodiments, the radar system 300 generates instructionsregarding adjusting the pose of at least one of the MIR receiver 304 orthe MIR transmitter 306. The processing circuit 312 can receive aninitial pose of the at least one of the MIR receiver 304 or the MIRtransmitter 306 from the position sensor 310. The processing circuit 312can receive, from the image capture device 308, an image of the subject100, and as described above, execute object recognition to detect thesubject 100 in the image and estimate the location of anatomicalfeatures of the subject 100 (e.g., estimate the heart to be in aparticular location). As such, the processing circuit 312 can generateinstructions for adjusting the initial pose of the at least one of theMIR receiver 304 or the MIR transmitter 306 using the detection of thesubject 100, such as to move the MIR receiver 304 and/or the MIRtransmitter 306 closer to or further from the subject 100, or to adjustan angle at which the MIR transmitter 306 transmits the transmittedradar signals towards the subject 100 or the MIR receiver 304 receivesthe radar return signals from the subject 100. For example, theprocessing circuit 312 can generate instructions to orient the MIRreceiver 304 to be pointed directly at the estimated location of theheart of the subject 100 to enable the processing circuit 312 to moreeffectively calculate cardiac parameters.

In some embodiments, the processing circuit 312 presents theinstructions using the user interface 320. As such, a user can use theinstructions to determine how to adjust the pose of the at least one ofthe MIR receiver 304 or the MIR transmitter 306 based on theinstructions. The processing circuit 312 can iteratively evaluate thepose of the at least one of the MIR receiver 304 or the MIR transmitter306, and update the presented instructions as the pose is adjusted. Insome embodiments, the radar system 300 includes an actuator coupled tothe at least one of the MIR receiver 304 or the MIR transmitter 306, andthe processing circuit 312 can cause the actuator to automaticallyadjust the pose.

In some embodiments, the MIR transceiver circuit 302 includes anelectronically scanned array (ESA), such as to selectively direct thetransmitted radar signals in particular directions. The processingcircuit 312 can generate instructions, in a similar manner as foradjusting the pose, to control operation of the ESA to steer thetransmitted radar signals transmitted by the ESA.

Tomography

The processing circuit 312 can control operation of the MIR transceivercircuit 302 to execute MIR tomography. For example, the control signalgenerator 404 can generate instructions so that the MIR transmitter 306can scan a plurality of sections of the subject 100, such as particulartwo-dimensional slices of interest. As described above, the processingcircuit 312 can generate the instructions to indicate a desired changein pose of the MIR receiver 304 and/or the MIR transmitter 306, or toelectronically steer the MIR transmitter 306, enabling the MIRtransceiver circuit 302 to selectively scan particular sections of thesubject 100.

Multiple Transmitters and/or Receivers

Referring further to FIG. 3, in some embodiments, the radar system 300includes one or more remote MIR receivers 324 and/or one or more remoteMIR transmitters 326, such as to enable bistatic and multistaticimplementations. For example, the radar system 300 may include multipletransmitters (MIR transmitter 306 and one or more MIR transmitters 326);the radar system 300 may include multiple receivers (MIR receiver 304and one or more MIR receivers 324). The remote MIR receivers 324 may besimilar to the MIR receiver 324, and the remote MIR transmitters 326 maybe similar to the MIR transmitter 306. The MIR transmitter 306 or theremote MIR transmitter 326 may be used to transmit the first radarsignal, and multiple receivers 304, 324 may receive second radar signalscorresponding to the first radar signal. For example, the MIRtransmitters 306, 326 can transmit a first radar signal, the receiver304 can receive a second radar signal corresponding to the first radarsignal (which may include components from any of transmission,reflection, refraction, absorption (and later emission), shadowing, orotherwise scattering of the first radar signal by the subject 100), andthe receiver 324 can receive a third radar signal (which may includecomponents from any of transmission, reflection, refraction, absorption(and later emission), shadowing, or otherwise scattering of the firstradar signal by the subject 100). The MIR transmitter 306 and the remoteMIR transmitter 326 may be used to each transmit first radar signals (orrespective first and second radar signals), and one or more of thereceivers 304, 324 may receive second or third radar signal(s)corresponding to the first radar signals. Where multiple transmitters306, 326 or receivers 304, 324 are used, various transmitters andreceivers may be collocated (e.g., implemented using the same device) orseparated from one another. In some embodiments, the transmitter(s) andreceiver(s) may be positioned in particular locations that enableeffective data capture and parameter determination, such as to avoid theradar signals passing through areas of the subject 100 that mayattenuate the radar signals (e.g., at certain frequencies, water contentof the subject 100 may attenuate the radar signals). For example, theMIR transmitter 306 can be positioned on a sternum region of the subject100, and the MIR receiver 304 can be positioned on a spinal cord regionof the subject 100, which can facilitate effective detection ofparameters associated with the heart or lungs of the patient. Inaddition to the MIR receiver 304, the remote MIR receiver 324 may bepositioned on an armpit region of the subject 100.

In some embodiments, the remote MIR receiver 324 and remote MIRtransmitter 326 may be provided in a same transceiver 322, or may beremotely located from one another. The processing circuit 312 mayreceive pose data regarding each remote MIR receiver 324 and each remoteMIR transmitter 326.

The processing circuit 312 can generate radar signal parameters for theone or more remote MIR transmitters 326 based on the radar signalparameter generated for the MIR transmitter 306. For example, theprocessing circuit 312 can generate the radar signal parameter for theremote MIR transmitter 326 to have a different pulse width or pulserepetition frequency than the radar signal parameter for the MIRtransmitter 306. The processing circuit 312 can encode a different noiseon the control signal provided to the remote MIR transmitter 326 than tothe MIR transmitter 306, to enable the MIR receivers 304, 324 to moreeffectively distinguish respective radar return signals.

The processing circuit 312 can combine radar return signals receivedfrom the MIR receiver 304 and the one or more MIR receivers 324 togenerate a composite impression of the subject 100. In some embodiments,the processing circuit 312 uses the pose data regarding the MIRreceivers 304, 324 and/or the MIR transmitters 306, 326 to combine theradar return signals. For example, the pose data, and a relationship ofthe pose data to the subject 100, can indicate different regions of thesubject 100 that are probed using the transmitted radar return signals;similarly, the pose data can indicate expected regions of the subject100 that would be represented by the radar return signals.

Portable Radar Systems

Referring now to FIG. 5, a portable radar system 500 is shown accordingto an embodiment of the present disclosure. The portable radar system500 can incorporate features of the portable radar system 120 describedwith reference to FIG. 1. The portable radar system 500 can be awearable device.

As shown in FIG. 5, the portable radar system 500 includes a sensorlayer 502 including an MIR sensor 504 coupled to a power supply 508 anda communications circuit 512. The MIR sensor 504 can incorporatefeatures of the MIR transceiver circuit 302 to transmit transmittedradar signals and receive radar return signals. The communicationscircuit 512 can incorporate features of the communications circuit 318described with reference to FIG. 3. In some embodiments, thecommunications circuit 318 uses a relatively low power communicationsprotocol, such as Bluetooth low energy.

The power supply 508 can have a relatively low capacity, given therelatively low power requirements of the MIR sensor 504 (e.g., less than0.1 Watt). Similarly, the portable radar system 500 can be safe forcontinuous wear and usage, due to the relatively low power of thetransmitted pulses (e.g., on the order of tens of microWatts).

The MIR sensor 504 can transmit sensor data using the communicationscircuit 512 to a remote device. In some embodiments, the MIR sensor 504transmits the sensor data to a portable electronic device (e.g., cellphone), which can perform functions of the radar system 300, such ascalculating physiological parameters based on the sensor data. As such,the portable radar system 500 can have relatively low size, weight,power, and/or cost.

The portable radar system 500 includes a housing layer 516. The housinglayer 516 can be shaped and configured to be worn by the subject 100. Insome embodiments, the housing layer 516 forms part of clothing or wornequipment (e.g., sports equipment), such as shoulder pads, helmets, orshoes. In some embodiments, the housing layer 516 is transparent to MIRsignals.

The portable radar system 500 can include an attachment member 520. Theattachment member 520 can enable the portable radar system 500 to beattached to a wearer or a body of the wearer (e.g., body of the subject100). For example, the attachment member 520 can include an adhesive, astrap, or other attachment components. By attaching the portable radarsystem 500 to the wearer, the portable radar system 500 can enablelongitudinal evaluation of physiological parameters in a medically safemanner (due to the low power output of the MIR signals).

Referring now to FIG. 6, a method 600 of operating an MIR is shownaccording to an embodiment of the present disclosure. The method 600 canbe performed using various systems described herein, including the radarsystem 110, the radar system 300, and the portable radar system 500.

At 605, a control signal defining a radar signal parameter of atransmitted (e.g., to be transmitted) radar signal by a control circuit.The control circuit can define the radar signal parameter based on anexpected physical response of the subject to the transmitted radarsignal that causes the radar return signal to have an expected signal tonoise ratio for the physiological parameter. The control circuit candefine the radar signal parameter to include at least one of afrequency, an amplitude, a pulse width, or a pulse repetition frequencyof the transmitted radar signal. At 610, the control circuit providesthe control signal to an MIR transceiver circuit.

At 615, the MIR transceiver circuit transmits the transmitted radarsignal based on the control signal. For example, the MIR transceivercircuit can use an antenna to output the transmitted radar signal. TheMIR transceiver circuit can transmit the transmitted radar signaltowards a subject.

At 620, the MIR transceiver circuit receives a radar return signal. Theradar return signal can correspond to the transmitted radar signal. Forexample, the radar return signal can be based on a reflection,refraction, absorption (and later emission), or other scattering of thetransmitted radar signal because of interaction with the subject.

At 625, the control circuit determines a physiological parameter basedon the radar return signal. The physiological parameter can includecardiac parameters, pulmonary parameters, gastrointestinal parameters,and fetal parameters. In some embodiments, the control circuitdetermines a likelihood of the subject having a medical condition basedon the physiological parameter. The control circuit can controloperation of the MIR transceiver circuit responsive to variousconditions, such as a predetermined schedule (e.g., to periodically orcontinuously output MIR signal and receive return signals), user input,or detecting physiological parameters that meet a trigger threshold(e.g., if the control circuit detects that the heart rate variationmeets a corresponding threshold, increase a rate of generating andreceiving MIR signals to sample the heart rate variation more often).

As utilized herein, the terms “approximately,” “about,” “substantially”,and similar terms are intended to have a broad meaning in harmony withthe common and accepted usage by those of ordinary skill in the art towhich the subject matter of this disclosure pertains. It should beunderstood by those of skill in the art who review this disclosure thatthese terms are intended to allow a description of certain featuresdescribed and claimed without restricting the scope of these features tothe precise numerical ranges provided. Accordingly, these terms shouldbe interpreted as indicating that insubstantial or inconsequentialmodifications or alterations of the subject matter described and claimedare considered to be within the scope of the disclosure as recited inthe appended claims.

It should be noted that the term “exemplary” and variations thereof, asused herein to describe various embodiments, are intended to indicatethat such embodiments are possible examples, representations, orillustrations of possible embodiments (and such terms are not intendedto connote that such embodiments are necessarily extraordinary orsuperlative examples).

The term “coupled” and variations thereof, as used herein, means thejoining of two members directly or indirectly to one another. Suchjoining may be stationary (e.g., permanent or fixed) or moveable (e.g.,removable or releasable). Such joining may be achieved with the twomembers coupled directly to each other, with the two members coupled toeach other using a separate intervening member and any additionalintermediate members coupled with one another, or with the two memberscoupled to each other using an intervening member that is integrallyformed as a single unitary body with one of the two members. If“coupled” or variations thereof are modified by an additional term(e.g., directly coupled), the generic definition of “coupled” providedabove is modified by the plain language meaning of the additional term(e.g., “directly coupled” means the joining of two members without anyseparate intervening member), resulting in a narrower definition thanthe generic definition of “coupled” provided above. Such coupling may bemechanical, electrical, or fluidic.

The term “or,” as used herein, is used in its inclusive sense (and notin its exclusive sense) so that when used to connect a list of elements,the term “or” means one, some, or all of the elements in the list.Conjunctive language such as the phrase “at least one of X, Y, and Z,”unless specifically stated otherwise, is understood to convey that anelement may be either X, Y, Z; X and Y; X and Z; Y and Z; or X, Y, and Z(i.e., any combination of X, Y, and Z). Thus, such conjunctive languageis not generally intended to imply that certain embodiments require atleast one of X, at least one of Y, and at least one of Z to each bepresent, unless otherwise indicated.

References herein to the positions of elements (e.g., “top,” “bottom,”“above,” “below”) are merely used to describe the orientation of variouselements in the FIGURES. It should be noted that the orientation ofvarious elements may differ according to other exemplary embodiments,and that such variations are intended to be encompassed by the presentdisclosure.

The hardware and data processing components used to implement thevarious processes, operations, illustrative logics, logical blocks,modules and circuits described in connection with the embodimentsdisclosed herein may be implemented or performed with a general purposesingle- or multi-chip processor, a digital signal processor (DSP), anapplication specific integrated circuit (ASIC), a field programmablegate array (FPGA), or other programmable logic device, discrete gate ortransistor logic, discrete hardware components, or any combinationthereof designed to perform the functions described herein. A generalpurpose processor may be a microprocessor, or, any conventionalprocessor, controller, microcontroller, or state machine. A processoralso may be implemented as a combination of computing devices, such as acombination of a DSP and a microprocessor, a plurality ofmicroprocessors, one or more microprocessors in conjunction with a DSPcore, or any other such configuration. In some embodiments, particularprocesses and methods may be performed by circuitry that is specific toa given function. The memory (e.g., memory, memory unit, storage device)may include one or more devices (e.g., RAM, ROM, Flash memory, hard diskstorage) for storing data and/or computer code for completing orfacilitating the various processes, layers and modules described in thepresent disclosure. The memory may be or include volatile memory ornon-volatile memory, and may include database components, object codecomponents, script components, or any other type of informationstructure for supporting the various activities and informationstructures described in the present disclosure. According to anexemplary embodiment, the memory is communicably connected to theprocessor via a processing circuit and includes computer code forexecuting (e.g., by the processing circuit or the processor) the one ormore processes described herein.

The present disclosure contemplates methods, systems and programproducts on any machine-readable media for accomplishing variousoperations. The embodiments of the present disclosure may be implementedusing existing computer processors, or by a special purpose computerprocessor for an appropriate system, incorporated for this or anotherpurpose, or by a hardwired system. Embodiments within the scope of thepresent disclosure include program products comprising machine-readablemedia for carrying or having machine-executable instructions or datastructures stored thereon. Such machine-readable media can be anyavailable media that can be accessed by a general purpose or specialpurpose computer or other machine with a processor. By way of example,such machine-readable media can comprise RAM, ROM, EPROM, EEPROM, orother optical disk storage, magnetic disk storage or other magneticstorage devices, or any other medium which can be used to carry or storedesired program code in the form of machine-executable instructions ordata structures and which can be accessed by a general purpose orspecial purpose computer or other machine with a processor. Combinationsof the above are also included within the scope of machine-readablemedia. Machine-executable instructions include, for example,instructions and data which cause a general purpose computer, specialpurpose computer, or special purpose processing machines to perform acertain function or group of functions.

Although the figures and description may illustrate a specific order ofmethod steps, the order of such steps may differ from what is depictedand described, unless specified differently above. Also, two or moresteps may be performed concurrently or with partial concurrence, unlessspecified differently above. Such variation may depend, for example, onthe software and hardware systems chosen and on designer choice. Allsuch variations are within the scope of the disclosure. Likewise,software implementations of the described methods could be accomplishedwith standard programming techniques with rule-based logic and otherlogic to accomplish the various connection steps, processing steps,comparison steps, and decision steps.

It is important to note that the construction and arrangement of the MIRand stethoscope devices and systems as shown in the various exemplaryembodiments is illustrative only. Additionally, any element disclosed inone embodiment may be incorporated or utilized with any other embodimentdisclosed herein. Although only one example of an element from oneembodiment that can be incorporated or utilized in another embodimenthas been described above, it should be appreciated that other elementsof the various embodiments may be incorporated or utilized with any ofthe other embodiments disclosed herein.

What is claimed is:
 1. A micro impulse radar (MIR) system, comprising: an MIR transceiver circuit configured to: transmit, towards a subject, at least one transmitted radar signal; and receive at least one radar return signal; and a control circuit configured to: generate a control signal defining a radar signal parameter of the at least one transmitted radar signal; provide the control signal to the MIR transceiver circuit to cause the MIR transceiver circuit to transmit the at least one transmitted signal based on the radar signal parameter; and determine, based on the at least one radar return signal, a physiological parameter of the subject.
 2. The MIR system of claim 1, wherein the control circuit defines the radar signal parameter based on an expected physical response of the subject to the transmitted radar signal that causes the radar return signal to have an expected signal to noise ratio for the physiological parameter.
 3. The MIR system of claim 2, wherein the control circuit determines the expected physical response based on an actual signal to noise ratio of a prior received radar return signal.
 4. The MIR system of claim 1, wherein the control circuit defines the radar signal parameter to include at least one of a frequency, an amplitude, a pulse width, or a pulse repetition frequency of the transmitted radar signal.
 5. The MIR system of claim 1, comprising a transmitter configured to transmit a third radar signal towards the subject, the transmitter spaced from a transmitter of the MIR transceiver circuit.
 6. The MIR system of claim 1, comprising a receiver configured to receive a third radar signal from the subject, the receiver spaced from a receiver of the MIR transceiver circuit, wherein the control circuit determines the physiological parameter based on the third radar signal.
 7. The MIR system of claim 6, wherein the control circuit executes a tomography algorithm based on the radar return signal and the third radar signal.
 8. The MIR system of claim 1, wherein the control circuit determines the physiological parameter to include a cardiac parameter including at least one of a heart rate variation, a heart volume, a heart stroke volume, a blood flow efficiency, a cardiac pulse shape, or a cardiac cycle-to-cycle variation.
 9. The MIR system of claim 1, wherein the control circuit determines the physiological parameter to include a pulmonary parameter including at least one of a breathing rate variation, a volume change in a chest of the subject, or an air exchange efficiency.
 10. The MIR system of claim 1, wherein the control circuit predicts a likelihood of the subject having a medical condition based on the physiological parameter.
 11. The MIR system of claim 10, comprising a historical database in which the control circuit maintains historical data regarding the physiological parameter, wherein the control circuit predicts the likelihood based on comparing the physiological parameter determined based on the radar return signal to the historical data.
 12. The MIR system of claim 11, wherein the control circuit maintains in the historical database, for each a plurality of subjects, an association between the physiological parameter and an indication of at least one medical condition, and predicts the likelihood of the subject having the at least one medical condition based on the association between the physiological parameter and the indication of at least one medical condition.
 13. The MIR system of claim 1, wherein the control circuit determines a fetal parameter based on the radar return signal.
 14. The MIR system of claim 1, wherein the control circuit determines a blood flow parameter including at least one of a blood flow velocity or a blood flow rate based on the radar return signal.
 15. The MIR system of claim 1, wherein the control circuit determines a cardiac parameter of the physiological parameter by identifying electrical activity corresponding to the cardiac parameter from the radar return signal.
 16. The MIR system of claim 1, wherein the control circuit determines a cardiac parameter of the physiological parameter based on a change in position of a cardiac tissue of the subject as a function of time.
 17. The MIR system of claim 1, wherein the control circuit determines a pulmonary parameter of the physiological parameter based on a change in position of a pulmonary tissue of the subject as a function of time.
 18. The MIR system of claim 1, comprising: an image capture device configured to detect an image of the subject; a position sensor configured to detect a position of the MIR transceiver circuit; and a user interface, wherein the control circuit uses the detected image and the detected position to calculate a change in at least one of a position or an orientation of the MIR transceiver circuit to direct the transmitted radar signal to a target location of the subject, and causes the user interface to present instructions corresponding to the change in the at least one of the position or the orientation.
 19. The MIR system of claim 1, wherein the control circuit is configured to calculate a signal to noise ratio of the physiological parameter based on the radar return signal and modify the radar signal parameter based on the signal to noise ratio.
 20. The MIR system of claim 1, comprising a wearable housing supporting the MIR transceiver circuit, the wearable housing including an attachment member to attach the wearable housing to the subject.
 21. The MIR system of claim 1, wherein the control circuit is configured to analyze the at least one radar return signal to determine each of a first cardiac parameter and a second cardiac parameter from the at least one radar return signal.
 22. The MIR system of claim 1, wherein the control circuit is configured to periodically generate and provide a plurality of control signals, receive a plurality of radar return signals corresponding to the plurality of control signals, and update the physiological parameter using the plurality of radar return signals.
 23. The MIR system of claim 1, further comprising at least one of one or more additional transmitters or one or more additional receivers to operate in a bistatic mode of operation or multi static mode of operation.
 24. The MIR system of claim 1, wherein the control circuit generates a signature of the subject using the physiological parameter.
 25. A method of operating a micro impulse radar (MIR), comprising: generating, by a control circuit, a control signal defining a radar signal parameter of a transmitted radar signal; providing, by the control circuit, the control signal to an MIR transceiver circuit; transmitting, by the MIR transceiver circuit, the transmitted radar signal based on the radar signal parameter; receiving, by the MIR transceiver circuit, a radar return signal; and determining, by the control circuit based on the radar return signal, a physiological parameter of a subject.
 26. The method of claim 25, comprising: defining the radar signal parameter based on an expected physical response of the subject to the transmitted radar signal that causes the radar return signal to have an expected signal to noise ratio for the physiological parameter.
 27. The method of claim 26, comprising: determining the expected physical response based on an actual signal to noise ratio of a prior received radar return signal.
 28. The method of claim 25, comprising: defining the radar signal parameter to include at least one of a frequency, an amplitude, a pulse width, or a pulse repetition frequency of the transmitted radar signal.
 29. The method of claim 25, comprising: transmitting, by a transmitter, a third radar signal towards the subject, the transmitter spaced from a transmitter of the MIR transceiver circuit.
 30. The method of claim 25, comprising: receiving, by a receiver, a third radar signal from the subject, the receiver spaced from a receiver of the MIR transceiver circuit; and determining the physiological parameter based on the third radar signal.
 31. The method of claim 30, comprising: executing a tomography algorithm based on the radar return signal and the third radar signal.
 32. The method of claim 25, comprising: determining a cardiac parameter of the physiological parameter to include at least one of a heart rate variation, a heart volume, a heart stroke volume, a blood flow efficiency, a cardiac pulse shape, or a cardiac cycle-to-cycle variation.
 33. The method of claim 25, comprising: determining a pulmonary parameter of the physiological parameter to include at least one of a breathing rate variation, a volume change in a chest of the subject, or an air exchange efficiency.
 34. The method of claim 25, comprising: predicting a likelihood of the subject having a medical condition based on the physiological parameter.
 35. The method of claim 34, comprising maintaining, in a historical database, historical data regarding physiological parameter; and predicting the likelihood based on comparing the physiological parameter determined based on the radar return signal to the historical data.
 36. The method of claim 35, comprising: maintaining in the historical database, for each a plurality of subjects, an association between the physiological parameter and an indication of at least one medical condition; and predicting the likelihood of the subject having the at least one medical condition based on the association between the physiological parameter and the indication of at least one medical condition.
 37. The method of claim 25, comprising: determining a fetal parameter based on the radar return signal.
 38. The method of claim 25, comprising: determining a blood flow parameter including at least one of a blood flow velocity or a blood flow rate based on the radar return signal.
 39. The method of claim 25, comprising: determining a cardiac parameter of the physiological parameter by extracting electrical activity corresponding to the cardiac parameter from the radar return signal.
 40. The method of claim 25, comprising: determining a cardiac parameter of the physiological parameter based on a change in position of a cardiac tissue of the subject as a function of time.
 41. The method of claim 25, comprising: determining a pulmonary parameter of the physiological parameter based on a change in position of a pulmonary tissue of the subject as a function of time.
 42. The method of claim 25, comprising: detecting, by an image capture device, an image of the subject; detecting, by a position sensor, a position of the MIR transceiver circuit; using the detected image and the detected position to calculate a change in at least one of a position or an orientation of the MIR transceiver circuit to direct the transmitted radar signal to a target location of the subject; and presenting, at a user interface, instructions corresponding to the change in the at least one of the position or the orientation.
 43. The method of claim 25, comprising: calculating a signal to noise ratio of the physiological parameter based on the radar return signal and modify the radar signal parameter based on the signal to noise ratio.
 44. The method of claim 25, further comprising analyzing the radar return signal to determine each of a first cardiac parameter and a second cardiac parameter from the at least one radar return signal.
 45. The method of claim 25, further comprising periodically generating and providing a plurality of control signals, receiving a plurality of radar return signals corresponding to the plurality of control signals, and updating the physiological parameter using the plurality of radar return signals.
 46. The method of claim 25, further comprising operating in a bistatic mode of operation or a multistatic mode of operation by using at least one of one or more additional transmitters or one or more additional receivers.
 47. The method of claim 25, further comprising generating a signature of the subject using the physiological parameter. 